Methods for flexible wireless channel association

RELATED APPLICATIONS

0001This application is a continuation of U.S. Ser. No. 09/963,671, filed Sep. 27, 2001, now U.S. Pat. No. 7,426,744.

0002The following application of common assignee is related to the present application, has the same filing date as the present application, and is herein incorporated by reference in its entirety: “Systems For Flexible Wireless Channel Association,” Ser. No. 11/822,983.

BACKGROUND OF THE INVENTION

00031. Field of the Invention

0004The present invention relates generally to communications networking, and more specifically, to allocating upstream bandwidth within a communications network.

00052. Related Art

0006Architects of communications networks continuously seek to achieve an optimal balance among various network characteristics. Such characteristics include bandwidth demand and quality of service parameters, such as latency, loss, or priority. For example, data-over-cable networks presently are expanding the variety of services traditionally provided to subscribers. In addition to television broadcasts, cable providers are offering telephony, messaging, and Internet services. As a result, additional bandwidth is needed to support the timely delivery of these services. Moreover, traditional cable broadcasts primarily require one-way communication from a cable service provider to a subscriber's home. As interactive or personal television services and other nontraditional cable services continue to be offered, communications media used to support one-way communications must now contend with an increased demand for bi-directional communications.

0007In a conventional cable television communications network, a communications device (such as a modem) requests bandwidth from a headend device prior to transmitting data to its destination. The headend device allocates bandwidth to the communications device based on availability and the competing demands from other communications devices. Typically, bandwidth is available to transmit signals downstream to the communications device. However in the upstream, bandwidth is more limited and must be arbitrated among the competing communications devices.

0008The downstream channel carries the information used by the communications devices to govern upstream transmissions. In a DOCSIS-compliant system, MAP messages are sent downstream to provide information about time slot assignments for the upstream channels associated with the downstream channel. In other words, the MAP messages assign one or more upstream channels to a specific communications device. The MAP messages also specify a time that may be used by the communications devices to transmit on an upstream channel and the type of data that may be transmitted. Moreover, these MAP messages are used by the headend device to predict the arrival of data from a communications device, the source of the data, and the type of data expected.

0009A headend device generally has one downstream channel and a finite number of upstream channels. To increment the quantity of upstream channels, the headend device can be chained to a second headend device through a master-slave interface. The first device runs in master mode, while the second device runs in slave mode. The master device sends MAP messages on its downstream channel across the master-slave interface to the slave device. The slave device, in turn, makes the MAP messages available to its upstream channels. If the master and slave devices each have, for example, eight upstream channels, using a master-slave interface permits the master device to receive data from a total of sixteen available upstream channels that can be used to support additional subscriber services.

0010Although a master-slave interface provides an avenue for supporting additional services, several drawbacks are attributable to this conventional approach. First, all upstream channels must be associated with a single downstream channel such that the upstream channels only receive MAP messages from the single downstream channel. Typically, master MAP messages are sent downstream from the master device to arbitrate asynchronous communications among the upstream channels of the slave device. If the slave device accepts the master MAP messages, no MAP message produced by the slave device can be used to arbitrate the upstream channels. In other words, if the downstream channel of the master device is associated with the upstream channels of the slave device, the downstream channel of the slave device cannot be used. Similarly, if less than the total available upstream channels of the slave device are associated with the downstream channel of the master device, the remaining upstream channels in the slave device cannot be used.

0011Conventional master-slave configurations are also inflexible and difficult to modify. The channel associations are fixed by the construction of the hardware. Therefore, the channel associations can only be changed by reconfiguring the hardware, namely to disable the master-slave interface. This cumbersome arrangement is not accommodating to changing load conditions in a dynamic, real time environment. The lack of system flexibility manifests an inefficient use of costly silicon and/or board resources.

0012Therefore, a communications device configured to support flexible channel association is needed to address the above problems.

BRIEF DESCRIPTION OF THE DRAWINGS/FIGURES

0013The accompanying drawings, which are incorporated herein and form part of the specification, illustrate the present invention and, together with the description, further serve to explain the principles of the invention and to enable a person skilled in the pertinent art to make and use the invention. In the drawings, like reference numbers indicate identical or functionally similar elements. Additionally, the leftmost digit(s) of a reference number identifies the drawing in which the reference number first appears.

0014<figref idref="DRAWINGS">FIG. 1</figref> illustrates a voice and data communications management system according to an embodiment of the present invention.

0015<figref idref="DRAWINGS">FIG. 2</figref> illustrates a media access controller according to an embodiment of the present invention.

0016<figref idref="DRAWINGS">FIG. 3</figref> illustrates a media access controller according to another embodiment of the present invention.

0017<figref idref="DRAWINGS">FIG. 4</figref> illustrates an operational flow diagram for altering the upstream channel associations according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Table of Contents

0000<ul id="ul0001" list-style="none"><li id="ul0001-0001" num="0018">I. Introduction</li><li id="ul0001-0002" num="0019">II. System Overview</li><li id="ul0001-0003" num="0020">Overview of Media Access Controller</li><li id="ul0001-0004" num="0021">IV. Upstream Channel Expansion and Association</li><li id="ul0001-0005" num="0022">V. Operational Flow for Flexible Channel Association</li><li id="ul0001-0006" num="0023">VI. Conclusion <br /> I. Introduction </li></ul>

0024The present invention includes a method and system for associating one or more upstream channels with more than one downstream channel of a communications device, such as, but not limited to, the headend device within a cable communications network. In a conventional cable communications system, the headend allocates upstream bandwidth among remotely distributed cable modems. This is achieved by dividing the upstream bandwidth into a finite number of channels, and dividing each channel into distinct time slots, such as minislots. The quantity of channels is determined and/or limited by the design and physical layout of the headend. For example if the headend is configured to include eight upstream channels and one downstream channel, the headend would use the downstream channel to send MAP messages or the like to each cable modem. The MAP messages specify a channel and minislot that a cable modem may use to send upstream transmissions.

0025Conventionally, the headend is physically configured to restrict its upstream channels to being associated with a single downstream channel. In other words, only one downstream channel is permitted to send MAP messages to the cable modems to designate upstream bandwidth. If a master-slave interface is used to provide additional upstream channels, all upstream channels of the slave device must be associated with the same downstream channel, primarily the downstream channel of the master device. As such, only the downstream channel of the master device is permitted to send MAP messages to designate bandwidth among the cable modems. Thus, this configuration prevents a slave device from being able to associate its upstream channels with its own downstream channel. Moreover, since conventional channel associations are fixed by hardware construction, the channel associations cannot be easily modified to accommodate changing network requirements.

0026However, the present invention provides a programmable implementation of channel association that permits upstream channels to be reallocated to accommodate changing load conditions. By virtue of the master-slave configuration of the present invention, the slave device can select or deselect its own downstream channel or the downstream channel of the master device. In other words, a slave device of the present invention can independently select different sources for MAP information to be utilized on its upstream channels. Furthermore, the downstream channel within a slave device remains useful even if the downstream channel of the master is operational. As a result, the present invention permits silicon and/or board resources to be more fully utilized.

0000II. System Overview

0027<figref idref="DRAWINGS">FIG. 1</figref> illustrates a voice and data communications management system <b>100</b> according to an embodiment of the present invention. System <b>100</b> includes a supervisory communications node <b>106</b> and one or more widely distributed remote communications nodes <b>102</b><i>a</i>-<b>102</b><i>n </i>(collectively referred to as “remote communications nodes <b>102</b>”).

0028System <b>100</b> can be implemented in any multimedia distribution network. Furthermore, it should be understood that the method and system of the present invention manage the exchange of voice, data, video, audio, messaging, graphics, other forms of media and/or multimedia, or any combination thereof.

0029Supervisory communications node <b>106</b> is centrally positioned to command and control interactions with and among remote communications nodes <b>102</b>. In an embodiment, supervisory communications node <b>106</b> is a component of a headend controller for a cable communications network. As such, supervisory communication node <b>106</b> is a cable modem termination system (CMTS) or a part thereof. In an embodiment, at least one remote communications node <b>102</b> is a cable modem or a part thereof. In another embodiment, supervisory communications node <b>106</b> is a CMTS and at least one remote communications node <b>102</b> is a component of a television set-top box.

0030As part of a cable modem, remote communications node <b>102</b> is configurable to host one or more services to a subscriber. The services include telephony, television broadcasts, pay-for-view, Internet communications (e.g., WWW), radio broadcasts, facsimile, file data transfer, electronic mailing services (email), messaging, video conferencing, live or time-delayed media feeds (such as, speeches, debates, presentations, infomercials, news reports, sporting events, concerts, etc.), or the like.

0031Each remote communications node <b>102</b> is assigned one or more service identifier (SID) codes that supervisory communications node <b>106</b> uses to allocate bandwidth. A SID is used primarily to identify a specific flow from a remote communications node <b>102</b>. However, as apparent to one skilled in the relevant art(s), other identifiers can be assigned to distinguish between the remote communications nodes <b>102</b> and/or the flow of traffic therefrom. Accordingly, in an embodiment, a SID or another type of identifier is assigned to identify a specific service affiliated with one or more remote communications nodes <b>102</b>. In an embodiment, a SID or another type of identifier is assigned to designate a particular service or group of services without regard to the source remote communications node <b>102</b>. In an embodiment, a SID or another type of identifier is assigned to designate a quality of service (QoS), such as voice or data at decreasing levels of priority, voice lines at different compression algorithms, best effort data, or the like. In an embodiment having multiple SIDs assigned to a single remote communications node, a primary SID or remote node identifier (RNID) is used to identify the remote communications node or a general flow from the remote communications node <b>102</b>, and a service class identifier (SCID) is used to specify a particular flow, service, or quality of service.

0032In an embodiment, supervisory communications node <b>106</b> and remote communications nodes <b>102</b> are integrated to support protocols such as Internet Protocol (IP), Transmission Control Protocol (TCP), User Datagram Protocol (UDP), Real Time Transport Protocol (RTP), Resource Reservation Protocol (RSVP), or the like.

0033Communications management system <b>100</b> also includes an intemodal infrastructure <b>105</b>. As shown in <figref idref="DRAWINGS">FIG. 1</figref>, intemodal infrastructure <b>105</b> provides interconnectivity among supervisory communications node <b>106</b> and remote communications nodes <b>102</b>. Internodal infrastructure <b>105</b> supports wired, wireless, or both transmission media, including satellite, terrestrial (e.g., fiber optic, copper, coaxial, hybrid fiber-coaxial (HFC), or the like), radio, microwave, and/or any other form or method of transmission.

0034All communications transmitted in the direction from supervisory communications node <b>106</b> towards remote communications nodes <b>102</b> are referred to as being in the downstream. In an embodiment, the downstream is divided into one or more downstream channels. Each downstream channel is configured to carry various types of information to remote communications nodes <b>102</b>. Such downstream information includes television signals, data packets (including IP datagrams), voice packets, control messages, and/or the like. In an embodiment, the downstream is formatted with a motion picture expert group (MPEG) transmission convergence sublayer. However, the present invention can be configured to support other data formats as would be apparent to one skilled in the relevant art. In an embodiment, supervisory communications node <b>106</b> implements time division multiplexing (TDM) to transmit continuous point-to-multipoint signals in the downstream.

0035The upstream represents all communications from remote communications nodes <b>102</b> towards supervisory communications node <b>106</b>. In an embodiment, the upstream is divided into one or more upstream channels. Each upstream channel carries bursts of packets from remote communications nodes <b>102</b> to supervisory communications node <b>106</b>. In the upstream, each frequency channel is broken into multiple assignable slots, and remote communications nodes <b>102</b> send a time division multiple access (TDMA) burst signal in an assigned slot.

0036As shown in <figref idref="DRAWINGS">FIG. 1</figref>, an embodiment of supervisory communications node <b>106</b> includes an upstream demodulator physical interface (US PHY) <b>108</b>, a downstream modulator physical interface (DS PHY) <b>110</b>, a media access controller (MAC) <b>112</b>, a memory <b>114</b> and a software application <b>120</b>. US PHY <b>108</b> forms the physical layer interface between supervisory communications node <b>106</b> and the upstream channel(s) of internodal infrastructure <b>105</b>. Hence, all bursts from remote communications nodes <b>102</b> are received at US PHY <b>108</b>. US PHY <b>108</b> processes the bursts to decompress and/or extract voice, data, requests, and/or the like from remote communications nodes <b>102</b>.

0037Conversely, DS PHY <b>110</b> forms the physical layer interface between supervisory communications node <b>106</b> and the downstream channel(s) of internodal infrastructure <b>105</b>. Hence, voice, data (including television or radio signals) and/or control messages that are destined for one or more remote communications nodes <b>102</b> are collected at DS PHY <b>110</b> and transmitted to the respective remote communications nodes <b>102</b>. DS PHY <b>110</b> compresses and/or formats the information for downstream transmission.

0038MAC <b>112</b> receives the upstream signals from US PHY <b>108</b>, or provides the downstream signals to DS PHY <b>110</b>, as appropriate. MAC <b>112</b> operates as the lower sublayer of the data link layer of supervisory communications node <b>106</b>. As described greater detail below, MAC <b>112</b> supports fragmentation, concatenation, and/or error checking for signals transported over the physical layer.

0039Memory <b>114</b> interacts with MAC <b>112</b> to store the signals as they are processed by MAC <b>112</b>. Memory <b>114</b> also stores various auxiliary data used to support the processing activities. Such auxiliary data includes security protocols, identifiers, rules, policies and/or the like, as described in greater details below.

0040MAC <b>112</b> is connected to software application <b>120</b> over bus <b>118</b>, which is a convention bidirectional bus. Software application <b>120</b> operates on one or more processors to receive control messages, voice and/or data from MAC <b>112</b>, and implement further processing. As shown, software application <b>120</b> includes a classifier/router <b>124</b> and a bandwidth (BW) allocation controller <b>128</b>. BW allocation controller <b>128</b> manages upstream and/or downstream modulation and bandwidth allocation. Classifier/router <b>124</b> provides rules and policies for classifying and/or prioritizing communications with remote communications nodes <b>102</b>. Classifier/router <b>124</b> also routes signals from remote communications nodes <b>102</b> to a destined location over backbone network <b>140</b>.

0041Backbone network <b>140</b> is part of a wired, wireless, or combination of wired and wireless local area networks (LAN) or wide area networks (WAN), such as an organization's intranet, local internets, the global-based Internet (including the World Wide Web (WWW)), private enterprise networks, or the like. As such, supervisory communications node <b>106</b> utilizes backbone network <b>140</b> to communicate with another device or application external to communications management system <b>100</b>. The device or application can be a server, web browser, operating system, other types of information processing software (such as, word processing, spreadsheets, financial management, or the like), television or radio transmitter, another remote communications node <b>102</b>, another supervisory communications node <b>106</b>, or the like.

0000III. Overview of Media Access Controller

0042The present invention permits supervisory communications node <b>106</b> to be re-configured to increase its quantity of upstream and/or downstream channels. Specifically, the interface between US PHY <b>108</b> and MAC <b>112</b> provides a finite number of upstream channels. In an embodiment, each US PHY <b>108</b> receives a single upstream channel, and supplies upstream bursts to MAC <b>112</b> over a pin connection. For example, if eight US PHYs <b>108</b> are connected to MAC <b>112</b> through separate pins, MAC <b>112</b> would operate to receive eight upstream channels. Therefore, the quantity of channels can be increased or decreased by incrementing or decrementing, respectively, the number of US PHYs <b>108</b>. Although each US PHY <b>108</b> typically supports a single upstream channel, however, for simplicity of illustration, the term “US PHY <b>108</b>,” as used herein, refers to one or more US PHY <b>108</b> devices and therefore handles multiple upstream channels, unless expressly stated otherwise.

0043Thus, the quantity of upstream channels is restricted by hardware design. However, a master interface and/or a slave interface permit additional channels to be associated with MAC <b>112</b>. <figref idref="DRAWINGS">FIG. 2</figref> illustrates an embodiment of MAC <b>112</b> configured for upstream channel expansion via a master and/or slave interface. In an embodiment, MAC <b>112</b> is an integrated circuit within a CMTS (shown in <figref idref="DRAWINGS">FIG. 1</figref> as supervisory communications node <b>106</b>). Accordingly, MAC <b>112</b> performs a variety of protocol processes defined by the Data Over Cable System Interface Specification (DOCSIS) for governing cable communications. The DOCSIS protocol processing includes interfacing with US PHY <b>108</b> and DS PHY <b>110</b>, encrypting and decrypting data, storing packet data in queues, and/or DMA functions to exchange data with memory <b>114</b>. Although the present invention is described in reference to DOCSIS protocol processing, it should be understood that the present invention is intended to be inclusive of other types of communication protocols governing multimedia distribution networks.

0044<figref idref="DRAWINGS">FIG. 2</figref> shows the components of MAC <b>112</b> according to an embodiment of the present invention. MAC <b>112</b> includes an upstream processor <b>204</b>, a MAP parse <b>214</b>, a downstream PHY MAP interface (I/F) <b>216</b>, an downstream processor <b>224</b>, and an input/output (I/O) arbitrator <b>228</b>. The MAC components communicate over bus <b>232</b>. In an embodiment, bus <b>232</b> is an internal-only split transaction bus with built-in arbitration to allow the components to communicate with each other with a shared memory interface to memory <b>114</b>.

0045Upstream processor <b>204</b> receives signals (including voice, data, bandwidth requests, and/or the like) from US PHY <b>108</b>. Upstream processor <b>204</b> prioritizes and processes the signals according to DOCSIS protocols. Upon completion, upstream processor <b>204</b> forwards the signals to a priority queue for further processing. The priority queues are located in memory <b>114</b>.

0046Bus <b>232</b> supports the transfer of signals among upstream processor <b>204</b>, memory <b>114</b>, and I/<b>0</b> arbitrator <b>228</b>. I/<b>0</b> arbitrator <b>228</b> manages the flow of signals between MAC <b>112</b> and software application <b>120</b>. Particularly, I/<b>0</b> arbitrator <b>228</b> interfaces with bus <b>118</b> to deliver the signals to software application <b>120</b>. I/O arbitrator <b>228</b> also receives signals from software application <b>120</b>. Such signals include broadcast signals, control messages, and/or the like to be transported downstream. These signals are typically stored in memory <b>114</b> until MAC <b>112</b> is ready to process them.

0047Downstream processor <b>224</b> interacts with bus <b>232</b> to receive the downstream signals from memory <b>114</b>. Downstream processor <b>224</b> formats and prepares the signals for delivery to DS PHY <b>110</b>. If the downstream signals include MAP messages, the MAP messages also are delivered to DS PHY <b>110</b>. The MAP messages subsequently are transmitted to the designated remote communications node(s) <b>102</b> to arbitrate the upstream channels of MAC <b>112</b>.

0048Downstream processor <b>224</b> also is connected to MAP parse <b>214</b>, and permits MAP parse <b>214</b> to monitor the downstream signals. Accordingly, the MAP messages are detected or extracted from the downstream signals by MAP parse <b>214</b>. Additionally, MAP parse <b>214</b> receives MAP messages from the MAP slave interface to MAC <b>112</b>. On receipt of MAP messages from downstream processor <b>224</b> and/or the MAP slave interface, MAP parse <b>214</b> forwards the MAP messages to MAP I/F <b>216</b>. MAP I/F <b>216</b> forwards the MAP messages to US PHY <b>108</b>. US PHY <b>108</b> uses the information to anticipate and/or demodulate the next upstream burst from remote communications nodes <b>102</b><i>a</i>-<b>102</b><i>n. </i>

0049MAC <b>112</b> is configured to operate, on a channel-by-channel basis, as a master device for a second MAC <b>112</b> operating as a slave device, and vice versa. As such, MAP parse <b>214</b> extracts and/or filters MAP messages that are designated for the slave MAC <b>112</b>. MAP parse <b>214</b> sends the MAP messages over the MAP master interface to the slave MAC <b>112</b>.

0050Hence, <figref idref="DRAWINGS">FIG. 2</figref> illustrates an embodiment of a MAC <b>112</b> capable of increasing the quantity of channels associated with supervisory communications node <b>106</b>. As described, MAC <b>112</b> sends MAP messages to designate the upstream bursts received by US PHY <b>108</b>. A master interface and a slave interface permit additional channels to be associated with MAC <b>112</b>. As such, if MAC <b>112</b> is restricted to servicing, for example, eight upstream channels, the master and/or slave interfaces can be used to connect a second MAC <b>112</b> make available an additional eight upstream channels.

0000IV. Upstream Channel Expansion and Association

0051The method and system of the present invention permit the association one or more upstream channels with more than one downstream channel. For example, a conventional cable headend device only allows its upstream channels to be associated with one downstream channel. Additionally if a master-slave interface is used to increase the number of available upstream channels, all upstream channels of the slave device must be associated with the same downstream channel, primarily the downstream channel of the master device. Moreover, conventional channel associations are fixed by hardware construction.

0052However, the present invention provides a programmable implementation of channel association that permits upstream channels to be reallocated to accommodate changing load conditions. Referring to the master and slave interfaces of <figref idref="DRAWINGS">FIG. 2</figref>, MAP parse <b>214</b> is enabled to switch between slave and master modes to select or deselect either the downstream channel of its governing MAC <b>112</b>, or the downstream channel of another MAC <b>112</b>. The expression “governing MAC <b>112</b>” as used herein refers to the actual MAC <b>112</b> that MAP parse <b>214</b> is a component thereof, as opposed to being coupled thereto via a master or slave interface.

0053<figref idref="DRAWINGS">FIG. 3</figref> shows the components of MAP parse <b>214</b> according to an embodiment of the present invention. MAP parse <b>214</b> includes a MAP extract <b>304</b>, a primary filter <b>308</b>, a slave filter <b>312</b>, and a parse processor <b>316</b>. MAP extract <b>304</b> monitors the downstream signals as they are being processed by downstream processor <b>224</b>. If MAP messages are detected in the downstream signals, MAP extract <b>304</b> sends the MAP messages to either primary filter <b>308</b> and/or a slave device over the MAP master interface. Primary filter <b>308</b> processes the MAP messages by upstream channel and decides whether to accept the MAP message for the designated upstream channel.

0054Similarly, slave filter <b>312</b> receives MAP messages from the MAP slave interface to MAC <b>112</b>. In an embodiment, MAC <b>112</b> operates as a slave device to another MAC <b>112</b> that is operating as a master device. MAP messages from the master MAC <b>112</b> are transmitted over the MAP slave interface to slave filter <b>312</b>. Slave filter <b>312</b> sorts the MAP message by upstream channel and determines whether to accept the MAP message. If slave filter <b>312</b> accepts the MAP messages, slave filter <b>312</b> synchronizes the signal carrying the MAP messages to a local system clock for MAC <b>112</b>.

0055In an embodiment, primary filter <b>308</b> and slave filter <b>312</b> both contain registers the enable the filters to decide whether to accept or reject MAP messages. As such, the registers, in essence, identify whether the properties of a particular upstream channel can be configured indirectly by a remote MAC <b>112</b> or by the local governing MAC <b>112</b>. In an embodiment, the registers include a channel identifier that designates an upstream channel. The registers also includes an interface bit that enables or disables the master mode or slave mode. In master mode, the interface bit is set to enable the local MAC <b>112</b> to directly configure the upstream channel designated by the channel identifier. In slave mode, the interface bit is set to enable the remote MAC <b>112</b> to indirectly configure the upstream channel designated by the channel identifier.

0056In other words, the registers decide whether primary filter <b>308</b> or slave filter <b>312</b> will accept or reject MAP messages from MAP extract <b>304</b> or the MAP slave interface, respectively. When the registers are set to permit primary filter <b>308</b> to accept MAP messages from MAP extract <b>304</b>, MAC <b>112</b> is operating in master mode for the designated upstream channels. As such, the accepted MAP messages from primary filter <b>308</b> are forwarded to parse processor <b>316</b>. However when the registers are set to permit slave filter <b>312</b> to accept MAP messages from the MAP slave interface, MAC <b>112</b> is operating in slave mode for the designated upstream channels. As such, the accepted MAP messages from slave filter <b>312</b> are forwarded to parse processor <b>316</b>.

0057Parse processor <b>316</b> receives MAP messages that have been accepted, authorized, and/or authenticated by slave filter <b>312</b> and/or primary filter <b>308</b>. Parse processor <b>316</b> prepares the MAP messages to be transmitted to US PHY <b>108</b>. In an embodiment, parse processor <b>316</b> sends the entire MAP message to US PHY <b>108</b>. In another embodiment, parse processor <b>316</b> translates the MAP messages to identify or specify the SID, interval usage code (IUC), length, minislot count, and/or minislot offset for each incoming burst. As such, only this data is sent to US PHY <b>108</b>.

0058Prior to sending the MAP messages to US PHY <b>108</b>, parse processor <b>316</b> forwards the MAP messages to MAP FIFO <b>320</b><i>a</i>-<b>320</b><i>f</i>. The MAP messages for each upstream channel are stored in an appropriate MAP FIFO <b>320</b><i>a</i>-<b>320</b><i>f </i>that is designated for each upstream channel. In this embodiment, six upstream channels are included; however as described above, the present invention permits more or less upstream channels to be included as determined by the hardware configuration.

0059Subsequently, the MAP FIFO <b>320</b><i>a</i>-<b>320</b><i>f </i>are emptied by the associated US PHY MAP I/F <b>216</b><i>a</i>-<b>216</b><i>f</i>. The MAP messages are then transferred to US PHY <b>108</b>. Although only one US PHY <b>108</b> is illustrated in <figref idref="DRAWINGS">FIG. 1</figref>, in an embodiment, a US PHY <b>108</b> is provided for each channel. Therefore, referring to <figref idref="DRAWINGS">FIG. 3</figref>, each US PHY MAP I/F <b>216</b><i>a</i>-<b>216</b><i>f </i>is likewise linked to a separate US PHY <b>108</b> for the designated upstream channel.

0060<figref idref="DRAWINGS">FIG. 3</figref> only illustrate a single master interface and slave interface for sending and receiving, respectively, MAP messages. However, the present invention includes configurations having multiple slave and/or master devices. As such, a plurality of MAP master interfaces can be included to permit MAP messages to be transmitted to a plurality of slave MACs <b>112</b>. Likewise, a plurality of slave filters <b>312</b> can be disposed in MAP parse <b>214</b> and operable to receive MAP messages from a plurality of master MACs <b>214</b>. Registers are provided to determine whether the MAP messages are accepted or rejected from each of the plurality of master MACs <b>214</b>. Thus, MAC <b>214</b> is configurable to support a single or multiple slave and/or master devices.

0000V. Operational Flow for Flexible Channel Association

0061The present invention implements a flexible channel association scheme that permits upstream channels of MAC <b>112</b> to be reallocated as required. Referring to <figref idref="DRAWINGS">FIG. 4</figref>, flowchart <b>400</b> represents the general operational flow of an embodiment of the present invention. More specifically, flowchart <b>400</b> shows an example of a control flow for managing the channel association of one or more upstream channels of MAC <b>112</b>.

0062The control flow of flowchart <b>400</b> begins at step <b>401</b> and passes immediately to step <b>404</b>. At step <b>404</b>, MAP parse <b>214</b> (shown in <figref idref="DRAWINGS">FIG. 2</figref>) detects or receives a MAP signal containing MAP messages from a primary or secondary source. Referring back to <figref idref="DRAWINGS">FIG. 2</figref>, downstream processor <b>224</b> serves as the primary source of MAP signals delivered to MAP parse <b>214</b>, and a MAP slave interface serves as the secondary source of MAP signals.

0063At step <b>408</b>, MAP parse <b>214</b> processes the MAP signal according to source. If the MAP signal arrives from the primary source, the control flow passes to step <b>412</b>. However, if the MAP signal arrives from the secondary source, the control flow passes to step <b>420</b>.

0064Considering the primary source, downstream processor <b>224</b> formats and prepares downstream signals that are destined for remote communications nodes <b>102</b>, as described above in reference to <figref idref="DRAWINGS">FIG. 2</figref>. If the downstream signal includes MAP messages, MAP extract <b>304</b> (shown in <figref idref="DRAWINGS">FIG. 3</figref>) detects and/or receives the MAP messages from the downstream signal.

0065At step <b>412</b>, MAP extract <b>304</b> determines whether the MAP signal is intended to govern the upstream channels of a slave MAC <b>112</b>, in addition to or in lieu of governing the upstream channels of its own MAC <b>112</b>. The destination of the MAP signal is determined by reading a header frame or like information including in the MAP signal.

0066If the MAP signal is destined for a slave MAC <b>112</b>, the control passes to step <b>416</b>. At step <b>416</b>, the MAP signal is sent over the MAP master interface to the other MAC <b>112</b> where the MAP signal is received by a MAP parse <b>214</b> resident to the other MAC <b>112</b>.

0067On the other hand, control passes to step <b>420</b> if the MAP signal is either not destined for a slave MAC <b>112</b> or destined for both a slave MAC and one or more upstream channels of the local governing MAC <b>112</b>. At step <b>420</b>, the MAP signal is driven to primary filter <b>308</b> (shown in <figref idref="DRAWINGS">FIG. 3</figref>).

0068Referring back to step <b>408</b>, control also passes to step <b>420</b> if the MAP signal enters MAP parse <b>214</b> from the secondary source. With regard to the secondary source, the MAP slave interface drives MAP signals from a remote MAC <b>112</b> to slave filter <b>312</b> (shown in <figref idref="DRAWINGS">FIG. 3</figref>). Therefore, MAP parse <b>214</b> is operable to receive MAP signals into either slave filter <b>312</b> or MAP extract <b>304</b>. As a master device, MAC <b>112</b> receives MAP signals in its MAP extract <b>304</b>, and when operating in slave mode, MAC <b>112</b> receives MAP signals in its slave filter <b>312</b>.

0069At step <b>420</b>, slave filter <b>312</b> or primary filter <b>308</b> determines the upstream channel(s) the MAP signal is intended to control. This data is determined by reading a header frame or like information included in the MAP signal. Accordingly, the MAP signal is filtered, sorted, and/or queued by upstream channel.

0070At step <b>424</b>, primary filter <b>308</b> or slave filter <b>312</b> authenticates the MAP signal to determine whether the primary source (i.e., the governing MAC <b>112</b>) or secondary source (i.e., a remote MAC <b>112</b>), respectively, has the authority to send MAP signals to arbitrate the designated upstream channel(s). In other words, on a channel-by-channel basis, slave filter <b>312</b> or primary filter <b>308</b> determines whether MAC <b>112</b> will function as a slave device or master device.

0071In an embodiment, slave filter <b>312</b> or primary filter <b>308</b> uses registers to authenticate the MAP signal. As such, the registers are used to determine which source has the authority to send a MAP signal to the designated upstream channel(s). As discussed above in reference to <figref idref="DRAWINGS">FIG. 3</figref>, the registers are used to compare the MAP signal to channel and/or interface bits for the designated upstream channel(s). Software application <b>120</b> provides authorization instructions to set and/or update the channel and/or interface bits to identify which source(s) has authority to configure and/or assign the upstream channels. In an embodiment, the registers are updated, in real time or near term, as the authorization is specified or changed. Authorization is specified or changed to optimally balance the load requirements of the application(s) being serviced. This includes the application(s) being serviced by either the remote MAC <b>112</b> or local MAC <b>112</b>.

0072If the source of the MAP signal lacks authority for the designated upstream channel, the MAP signal is rejected. Hence the control flow passes to step <b>495</b>. Additionally in an embodiment, if no channel and/or interface bit is available for the designated upstream channel, the MAP signal is rejected and the control flow passes to step <b>495</b>.

0073If, on the other hand, the source is authorized for the designated upstream channel, the control flow passes to step <b>428</b>. At step <b>428</b>, parse processor <b>316</b> receives MAP signals that have been accepted, authorized, and/or authenticated by slave filter <b>312</b> and/or primary filter <b>308</b>. Parse processor <b>316</b> processes the MAP messages (i.e., MAP information elements) from the MAP signals, and prepares the MAP messages to be transmitted to US PHY <b>108</b>. In an embodiment, parse processor <b>316</b> prepares the entire MAP message to be sent to US PHY <b>108</b>. In another embodiment, parse processor <b>316</b> translates the MAP messages to identify or specify the SID, IUC, length, minislot count, and/or minislot offset for each incoming burst. As such, only this data prepared to be sent to US PHY <b>108</b>.

0074At step <b>432</b>, parse processor <b>316</b> drives the MAP messages to the appropriate MAP FIFO <b>320</b><i>a</i>-<b>320</b><i>f</i>. MAP messages for each upstream channel are stored in an appropriate MAP FIFO <b>320</b><i>a</i>-<b>320</b><i>f </i>that is designated for each upstream channel.

0075At step <b>436</b>, MAP FIFO <b>320</b><i>a</i>-<b>320</b><i>f </i>are emptied at the appropriate time to send the MAP messages to the designated US PHY MAP I/F <b>216</b><i>a</i>-<b>216</b><i>f </i>for delivery to US PHY <b>108</b>. The MAP messages are then transferred to US PHY <b>108</b>. After the MAP messages have been transmitted, or rejected as described above, the control flow ends as indicated by step <b>495</b>. Accordingly, the control flow of flowchart <b>400</b> describes a process for assigning and re-assigning channel associations in response to changing load demands.

0076The present invention allows the association of groups of upstream channels with more than one downstream channel of a communications device. It also allows the associations to be changed. Specifically, MAC <b>112</b> can independently select different sources for MAP information for each upstream channel it controls. Thus, the downstream channel controlled by the slave device is still useful. The present invention allows significantly greater flexibility in the association of upstream channels and downstream channels at a MAC <b>112</b>. Moreover, the present invention features improved MAP master-slave functionality. The improved flexibility makes the system more adaptable and improves the utilization of silicon and/or board resources.

0000VI. Conclusion

0077<figref idref="DRAWINGS">FIGS. 1-4</figref> are conceptual illustrations that allow an easy explanation of the present invention. That is, the same piece of hardware or module of software can perform one or more of the blocks. It should also be understood that embodiments of the present invention can be implemented in hardware, software, or a combination thereof. In such an embodiment, the various components and steps would be implemented in hardware and/or software to perform the functions of the present invention.

0078While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example, and not limitation. It will be apparent to persons skilled in the relevant art(s) that various changes in form and detail can be made therein without departing from the spirit and scope of the invention. Moreover, it should be understood that the method and system of the present invention should not be limited to transmissions between cable modems and headends. The present invention can be implemented in any multi-nodal communications environment governed by a centralized node. The nodes can include communication gateways, switches, routers, Internet access facilities, servers, personal computers, enhanced telephones, personal digital assistants (PDA), televisions, set-top boxes, or the like. Thus, the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.